Rēg'ū-lā'tor, n.

n. [Sp. regulador, It. regolatore.] 1. One who regulates; specifically, in the United States, one of a band of men who, in the absence or inadequacy of ordinary legal authority, take into their own hands the punishment of crime and the regulation of society. A few stood neutral, or declared in favor of the Regulators. Bancroft. 2. (Mech.) That which serves to regulate or control; as, (a.) The lever or index in a watch, which controls the effective length of the hair or balance-spring, by means of the curb-pins which it carries, and thus regulates the vibrations of the balance. (b.) A clock of superior excellence, usually having a compensating pendulum and a dead-beat escapement, used by watch-makers for regulating watches. (c.) The throttle-valve of a steam-engine. [Eng.] (d.) In general, any contrivance, usually self-acting, by which motion is checked and regulated, either by limiting the source or obstructing its effects, as the governor of a steam-engine, the pendulum or balance of a time-piece, a fly or fan-wheel, or the like.